JP4840690B2 - Pipe end anticorrosion material and piping structure - Google Patents

Description

  The present invention relates to a pipe end anticorrosion member mounted on an end of an inner surface resin-coated steel pipe constituting a water distribution pipe and the like, and a piping structure using the same.

  In distribution pipes, for example, water supply pipes or hot water supply pipes, SUS steel pipes, resin pipes, or inner surface resin-coated steel pipes are used, especially when pipe costs (material costs and construction costs) are important. Lined steel pipes whose inner surfaces are coated with resin are frequently used. As the lining steel pipe, a polyethylene powder lining steel pipe for water supply (SGP-PA pipe) or a vinyl chloride lining steel pipe for water supply (SGP-VA pipe) is frequently used. Since this lining steel pipe is cut to a predetermined length at the construction site, in order to prevent corrosion of the steel pipe exposed at the cut end, pipe end anti-corrosion members are attached to the cut end and then pipe connection is made by various joints. Has been done.

  In order to reduce the pipe construction cost, for example, pipe end anticorrosion members described in Patent Document 1 and Patent Document 2 have been proposed in order to enable corrosion prevention of the pipe end by a simple operation. First, Patent Document 1 describes an anticorrosive core for an adhesive-attached pipe made of a corrosion-resistant material such as a synthetic resin. The pipe anticorrosion core has an annular bottom wall joined to the pipe end surface, and an inner wall joined to the inner surface of the inner surface resin-coated steel pipe and an outer wall joined to the outer surface of the pipe are formed in a U-shaped cross section in the same direction, An adhesive is injected into the U-shaped portion, and the surface is covered with a protective sheet.

  Further, in Patent Document 2, when a ring body that can be externally fitted to an end portion of a pipe body (for example, a ductile pipe having an inner peripheral surface subjected to powder lining) is attached to the pipe body, An anticorrosion ring for a tubular body is described in which an inward projecting piece facing the tip is provided, and a rubber-based adhesive bonded to the tip surface of the tubular body is provided on the facing surface of the inward projecting piece.

Japanese Utility Model Publication No. 61-99794 (first page, FIGS. 1 and 2) Japanese Utility Model Publication No. 7-22198 (first page, FIG. 1, FIG. 2)

  According to the above pipe end anticorrosion member (corrosion prevention core or anticorrosion ring), it is possible to easily perform the anticorrosion work, but there are the following problems when applied to a normal water pipe. It was discovered. That is, since two types of inner surface resin-coated steel pipes are used in ordinary water supply pipes, it is necessary to obtain an anticorrosion effect for any of the inner surface resin-coated steel pipes. However, since the water absorption rate of the resin coated on the inner surface of the original pipe is different, the coating thickness is different, so that the inner diameter is different even if the diameter (nominal diameter) is the same. That is, since the SGP-PA tube uses polyethylene having a water absorption rate (measured value according to JIS K 7209, the same applies hereinafter) of 0.04% or less, the coating thickness is about 0.30 to 0.50 mm. On the other hand, since the SGP-VA pipe uses vinyl chloride having a water absorption rate of about 0.4%, the coating thickness is about 1.5 to 2.5 mm. Therefore, when the diameter is 50 A, the inner diameter of the SGP-VA tube is 50.2 mm (actual value, the same applies hereinafter), whereas the inner diameter of the SGP-PA tube is 51.2 mm. For this reason, in the pipe end anticorrosion member (corrosion prevention core) described in Patent Document 1, the inner diameter of the outer wall joined to the inner surface of the inner surface resin-coated steel pipe is set to a dimension capable of receiving the SGP-VA pipe. However, when the anticorrosion core set to such a dimension is attached to the end surface of the SGP-PA pipe, a large gap is formed between the outer peripheral surface of the outer wall and the inner peripheral surface of the inner surface resin-coated steel pipe. The rubber-based adhesive provided on the inner wall of the pipe end anticorrosion member has an anticorrosive action at the pipe end and an adhesive action to fix the steel pipe to itself, but the flow velocity of the fluid flowing in the pipe is high (for example, 3 m / s or more) ), The tap water may enter the inside of the gap, and the adhesive may flow out into the pipe depending on the adhesive strength and the like, and sufficient corrosion resistance at the end of the pipe may not be obtained. Furthermore, when the adhesive flows out, the anticorrosion core may come out of the pipe end.

  Moreover, since the pipe end anticorrosion member (corrosion prevention ring) described in Patent Document 2 has a simple shape with an open inner surface side, it can be manufactured at a low cost. However, the anticorrosion ring and the pipe end are the ends of the adhesive and the steel pipe. Since it is joined only by fitting between the outer peripheral surface and the main body (flange portion), the joining force between the anticorrosion ring and the pipe end is weaker than that described in Patent Document 1, and the adhesive and tap water Since the contact area is large, the adhesive easily flows out, and there is a problem similar to that of the anticorrosion core of Patent Document 1.

  The object of the present invention is to solve the above problems and provide a pipe end anticorrosive member that can be firmly fixed to the end faces of a plurality of types of inner surface resin-coated steel pipes having different diameters and a pipe structure including the pipe end anticorrosive member. is there.

In order to achieve the above object, a pipe end anticorrosion member of the present invention is a pipe end anticorrosion consisting of a double ring-shaped main body made of a thermoplastic resin and an annular adhesive member in close contact with the end face of the inner surface resin-coated steel pipe. In the member, the double ring-shaped main body includes an outer flange portion that engages with an outer peripheral surface of the inner surface resin-coated steel pipe, an inner flange portion that engages with an inner peripheral surface of the inner surface resin-coated steel pipe, and the outer flange portion. And a bottom plate part integrally connecting the inner flange part,
Furthermore, the length (L1) of the outer flange portion and the length (L2) of the inner flange portion are the ratio of the length (L2) of the inner flange portion and the outer diameter (D) of the inner surface resin-coated steel pipe ( L2 / D)
(A) When L2 / D is 0.1 or more and less than 0.3, L2> L1,
(B) When L2 / D is 0.02 or more and less than 0.1, L1> L2
Is set to have a dimensional relationship of
There is no gap between the outer peripheral surface of the inner surface resin-coated steel pipe and the outer flange portion, and the engagement between the inner peripheral surface of the inner surface resin-coated steel pipe and the inner flange portion has a gap. Is.

  In the present invention, it is preferable that the double ring-shaped main body is made of polyethylene, and the adhesive member is made of unvulcanized butyl rubber.

  In the present invention, an SGP-PA pipe and an SGP-VA pipe can be used as the inner surface resin-coated steel pipe.

  The present invention provides a pipe structure comprising the above-mentioned inner surface resin-coated steel pipe, a pipe joint that requires pipe end anticorrosion treatment of the inner surface resin-coated steel pipe to be connected, and the pipe end anticorrosion member described above. Can be configured.

  According to the present invention, the length (L1) of the outer flange portion that receives the outer peripheral surface of the inner surface resin-coated steel pipe and the inner flange portion that forms the space into which the inner surface resin-coated steel tube is inserted between the outer flange portion. Since the length (L2) is set to have a specific relationship according to the ratio of the length (L2) of the inner flange portion to the outer diameter (D) of the inner surface resin-coated steel pipe, the fluid flowing in the pipe Even if it receives the flow-down resistance, a predetermined sealing anticorrosive force and adhesive force can be maintained without a part of the adhesive member flowing out from the gap between the inner and outer flange portions and the coated steel pipe. In particular, the outer peripheral surface of the inner surface resin-coated steel pipe and the outer flange portion are in close engagement with each other, and an engagement relationship in which a gap is formed between the inner peripheral surface of the inner surface resin-coated steel pipe and the inner flange portion. In this case, the adhesion force on the outer peripheral surface side is increased and the separation of the pipe end anticorrosive member can be prevented, and even if there is a gap on the inner peripheral surface side, the above-mentioned sealing anticorrosive force and adhesive force can be maintained at the same time. It is possible to handle different types of different tube types.

In particular, if the main body is made of polyolefin (for example, polyethylene) and the adhesive member is made of a sticky elastic body (for example, unvulcanized butyl rubber), the manufacturing cost is reduced and the adhesive strength is high. A pipe end anticorrosive member having high properties can be obtained. Specifically, by applying this pipe end anticorrosion member to an SGP-PA pipe or an SGP-VA pipe, a pipe free from defects such as red water can be obtained at low cost.
Moreover, the piping structure using this pipe end anticorrosion member can be widely used as long as it is a connection structure with a pipe joint that requires pipe end anticorrosion treatment, even if it is an inner surface resin-coated steel pipe other than the above.

The details of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a half sectional view showing an example of a pipe structure having a pipe end anticorrosive member according to an embodiment of the present invention, and FIG. 2 is an arrow view of FIG. 1 viewed from the direction A (the inner surface resin-coated steel pipe is not shown). 3 is an arrow view of FIG. 2 as viewed from the direction B (the inner surface resin-coated steel pipe is not shown), FIG. 4 is a cross-sectional view around the pipe end anticorrosion member showing an enlarged portion C of FIG. 1, and FIG. FIG. 6 is a sectional view showing an example of a pipe end anticorrosion member, and FIG. 7 is a cross sectional view showing another example of the pipe end anticorrosion member.

  The piping structure shown in FIGS. 1 to 4 is similar to the inner surface resin-coated steel pipe 10a having a pipe end anticorrosive member 6a (details will be described later) attached to the end, and the inner surface resin having the pipe end anticorrosive member 6b attached to the end. It has a structure in which the coated steel pipe 10 b is connected by a coupling type joint 1. The pipe joint is not limited to the coupling type joint as in this example, but is shown as a suitable example of a pipe structure that requires a pipe end anticorrosion structure.

  The inner surface resin-coated steel pipes 10a and 10b include original pipes 11a and 11b made of, for example, a carbon steel pipe (SGP pipe: JIS G 3452), and lining layers 12a and 12b formed on the inner surfaces thereof. In the following example, as the inner surface resin-coated steel pipes 10a and 10b, a polyethylene powder lining steel pipe (SGP-PA: see Japan Water Works Association Standard JWWA K132) or a raw pipe made of polyethylene powder pressed and fused to the inner surface of the original pipe. A hard vinyl chloride lined steel pipe (SGP-VA: see Japan Water Works Association Standard JWWA K116) having a vinyl chloride pipe in close contact with the inner surface is used.

  The coupling type joint 1 includes an elastically deformable housing 2 obtained by molding a thin plate made of a metal material having corrosion resistance such as austenitic stainless steel (for example, SUS304) into a C-shaped section, and the housing 2 is fastened. A fastening member 3, a packing 4 housed inside the housing 2, and holding members 5 a and 5 b provided on both sides of the packing 4 are provided.

  The fastening member 3 includes a rod washer 31 inserted into the folded portion 21a of the housing 2, a rod nut 32 inserted into the folded portion 21b, and a plurality (two in this example) screwed into the rod nut 32 from a direction orthogonal thereto. Bolts 33a and 33b, and spacers 34a and 34b that are set to penetrate the bolts 33a and 33b.

  The packing 4 is formed of, for example, an olefin rubber such as EPDM or a nitrile rubber such as NBR in order to ensure the sealing performance with the inner surface resin-coated steel pipes 10a and 10b, and is formed at the cylindrical portion 41 and both ends thereof. Lip portions 42a and 42b are provided.

  The holding members 5a and 5b are inclined inwardly from the end faces of the housing 2 and stop rings 51a and 51b that are in close contact with the end face of the packing 4 in order to prevent the inner resin-coated steel pipes 10a and 10b from moving in the axial direction. The grip rings 52 a and 52 b having the plurality of locking claws 521 a and 521 b and the wire rings 53 a and 53 b that press these members toward the end surface of the packing 4.

  Each member constituting the fastening member 3 and the holding members 5a and 5b can be formed of a metal material having the same corrosion resistance as that of the housing 2, for example.

  The inner surface resin-coated steel pipes 10a and 10b can be connected by the above-described coupling type joint 1 in the following procedure, for example. Inside the housing 2 in which the fastening member 3, the packing 4 and the holding members 5a and 5b are accommodated, the inner surface resin-coated steel pipes 10a and 10b having pipe end anticorrosive members 6a and 6b attached to the respective ends are inserted, and then bolts 33a. , 33b. As a result, the housing 2 is reduced in diameter, so that the lip portions 42a and 42b of the packing 4 are in close contact with the outer surfaces of the inner surface resin-coated steel tubes 10a and 10b, and the locking claws 521a and 521b of the grip rings 52a and 52b are inner surface resin-coated. The pipe connection is performed by biting into the outer surfaces of the steel pipes 10a and 10b.

  Details of the pipe end anticorrosion member 6a and a piping structure using the same (the same applies to the pipe end anticorrosion member 6b) will be described with reference to FIGS. As shown in FIG. 4, the pipe end anticorrosion member 6a (the pipe end anticorrosion member 6b is also the same) is held by the case 7 which is a double ring-shaped main body and the inner back wall thereof, and the end face of the inner surface resin-coated steel pipe 10a. A hollow disk-shaped adhesive member 8 in contact with.

  As shown in FIG. 5, the case 7 is provided with a hollow disk-shaped bottom plate portion 71, an outer flange portion 72 protruding in the axial direction at the outer edge portion thereof, and an axial direction protruding at the inner edge portion of the bottom plate portion 71. A space is formed between the outer flange portion 72 and the inner flange portion 73 so that the end portion of the inner surface resin-coated steel pipe is inserted between the inner flange portion 73 and the inner flange portion 73. The case 7 is made of a thermoplastic resin that can be manufactured by, for example, an injection molding method so that the case 7 can be manufactured at a low cost. Specifically, the case 7 is represented by polyethylene (PE) or polypropylene (PP). It is preferable to use a polyolefin-based resin, and PE is more preferable in consideration of heat resistance and mechanical strength.

The adhesive member 8 has a rubber-based adhesive in order to obtain a predetermined anticorrosion force and adhesive force when contacting the end surface of the inner surface resin-coated steel pipe, and to absorb axial variations of the inner surface resin-coated steel pipe. it is preferable to form the dosage, a copolymer of isobutene and a small amount of isoprene, exhibit good adhesion to metal, also chemically inert and acid or resistant strong rubber against alkali Is more preferable. In particular, unvulcanized butyl rubber obtained by processing vulcanized butyl rubber to impart viscosity and plasticity has very little internal stress (residual stress) and is extremely useful in the present invention.

  For example, in water supply pipes, 11 types of inner surface resin-coated steel pipes 10a having a diameter (nominal diameter) in the range of 20A to 200A are usually used, but the outer diameters of SGP-VA pipes and SGP-PA pipes are Even if (D) is the same, the inner diameters (Da, Db) are different, and as shown in Table 1, there is an inner diameter difference Δd (measured value) of 1.0 to 1.9 mm.

  Therefore, in the present invention, by appropriately setting the dimensions of the case 7 according to the diameter of the inner surface resin-coated steel pipe, the pipe end anticorrosive member can be bonded to any of the SGP-VA pipes and SGP-PA pipes having various diameters. The performance can be maintained.

When the diameter (nominal diameter) of the inner surface resin-coated steel pipe is 20A to 40A, the case 7 having a shape in which the inner flange portion 73 is slightly longer than the outer flange portion 72 is suitable as shown in FIG. 6, D1: outer diameter of the outer flange portion 72, D2: inner diameter of the outer flange portion 72, t1: thickness of the outer flange portion, L1: length of the outer flange portion, t2: thickness of the bottom plate portion, d1 : Inner diameter of the inner flange part, d2: outer diameter of the inner flange part, t3: thickness of the inner flange part, L2: length of the inner flange part, dp: inner diameter of the inner surface resin-coated steel pipe and corresponding to Da and Db in Table 1 Table 2 shows the dimensions of each part.
Here, the inner diameter D2 of the outer flange portion is set so as to have the same dimension as the outer diameter (D) of the inner surface resin-coated steel pipe and to have a dimensional tolerance with respect to D (for example, h6 / R7). ing. In other words, the engagement relationship has no gap. On the other hand, the relationship between the outer diameter d2 of the inner flange portion and the inner diameter dp of the inner surface resin-coated steel pipe is set so as to have dp> d2 and a gap g. However, in consideration of the dimensional tolerance, the gap g can be close to 0, but a gap is generally generated.

  When the inner diameter resin-coated steel pipe has a diameter (nominal diameter) of 50A to 200A, the case 7 having a shape in which the outer flange portion 72 is longer than the inner flange portion 73 is suitable as shown in FIG. In FIG. 7, D1: outer diameter of the outer flange, D2: inner diameter of the outer flange, t1: thickness of the outer flange, L1: length of the outer flange, t2: thickness of the bottom plate, d1: inner The inner diameter of the flange portion, d2: the outer diameter of the inner flange portion, t3: the thickness of the inner flange portion, L2: the length of the inner flange portion, dp: the inner diameter of the inner surface resin-coated steel pipe. Shown in In this case, the outer flange outer diameter D2 is set to the same dimension as the steel pipe outer diameter D and the same dimensional tolerance as described above. Similarly, a gap g is set between the outer diameter d2 of the inner flange portion and the steel pipe inner diameter dp.

  Next, in the state where the pipe end anticorrosive member 6a in which the adhesive member 8 made of unvulcanized butyl rubber is attached to the case 7 made of PE having the dimensions shown in Table 2 is attached to the end face of the inner surface resin-coated steel pipe, the JIS S3200-7 A similar leaching performance test (in-pipe flow rate: 3 m / s) was conducted. As a result, in any case, the iron concentration was 0.3 mg / L or less, and there was no abnormality in the odor (metal odor) (no red water was generated). It was confirmed that the pipe end of the steel pipe was properly protected against corrosion.

  For comparison, pipe end anticorrosion members using cases having the same dimensions as in Table 2 except that L1 = L2 = 6 mm were prepared for all the apertures (nominal diameters), and leaching was performed under the same conditions as above. As a result of the performance test method, the iron concentration exceeded 0.3 mg / L and any odor (metal odor) was observed in any case. It was confirmed that the tube end was not properly protected.

Therefore, when the dimensions of each part of the case shown in Table 2 are arranged based on the results of the above leaching performance test, the length (L1) of the outer flange portion and the length (L2) of the inner flange portion are the lengths of the inner flange portion. It can be seen that it is necessary to set so as to have the following relationship according to the ratio (L2 / D) between the length (L2) and the outer diameter (D) of the inner surface resin-coated steel pipe.
(A) When L2 / D is 0.1 or more and less than 0.3 (in this example, the diameter D corresponds to 20A to 40A), L2>L1;
(B) When L2 / D is 0.02 or more and less than 0.1 (in this example, the diameter D corresponds to 50A to 200A), L1> L2.

  The reason why the pipe end of the inner surface resin-coated steel pipe is normally prevented by the pipe end anticorrosive member having the above dimensional relationship is presumed to be as follows. As shown in FIG. 4, when tap water flows in the direction of the arrow X in a state where this pipe end anticorrosion member 6a is mounted on the end face of the inner face resin-coated steel pipe 10a, for example, the inner face of the inner face resin-coated steel pipe 10a and the inner flange portion 73 The tap water also flows into the annular space formed by the gap formed between them, and the adhesive member 8 is compressed. Here, if the length (L2) of the inner flange portion 73 is not set to an appropriate dimension, a part of the adhesive member 8 may be dragged out into the annular space and eventually flow out in the direction of the arrow Y in the figure. Increase. At this time, if there is a gap between the outer flange 72 and the outer peripheral surface of the inner surface resin-coated steel pipe 10a, water pressure is also applied to the annular space from here and further acts in the direction in which the adhesive member 8 is dragged out.

  Therefore, when the diameter (nominal diameter) is relatively small, for example, 20A to 40A, the ratio (L2 / D2) of the length L2 of the inner flange portion 73 to the outer diameter D of the inner surface resin-coated steel pipe 10a of the pipe end anticorrosive member 6a is More than 0.1 and less than 0.3. In this case, as shown in FIG. 6, by making L2 longer than L1, a part of the adhesive member 8 is dragged into the annular space (gap). It has been found that even if it works, it is easily held inside the case 7 by the appropriate length L2. Therefore, even when the flow velocity in the pipe is fast (for example, 3 m / s or more), the pipe end anticorrosion member 6a is prevented from being detached from the end portion of the inner surface resin-coated steel pipe 10a. Furthermore, eliminating the gap between the outer flange 72 and the outer peripheral surface of the inner surface resin-coated steel pipe 10a is more effective because the influence of water pressure applied from here is eliminated.

  On the other hand, as shown in FIG. 7, when the diameter (nominal diameter) is as large as 50A to 200A, for example, the ratio (L2 / D) of the length L2 of the inner flange portion 73 to the outer diameter D of the inner surface resin-coated steel pipe 10a. Is 0.02 or more and less than 0.1. In this case, as shown in FIG. 7, L1 is made longer than L2. Thereby, the contact length and area of the outer peripheral surface of the inner surface resin-coated steel pipe 10a and the inner surface of the outer flange portion 72 are increased. The pipe end anticorrosion member having a large diameter is subjected to a greater water pressure, but the contact length and the contact area on the outer flange side are increased, so that the resistance strength on the outer peripheral side is strong and the separation preventing effect is high. Therefore, it is less likely that a part of the adhesive member 8 is dragged out into the annular space, and a decrease in the adhesive strength between the pipe end anticorrosive member 6a and the resin-coated steel pipe 10a is small. Therefore, even when the flow velocity in the pipe is fast (for example, 3 m / s or more), it is possible to prevent the pipe end anticorrosion member 6a from being detached from the end of the inner surface resin-coated steel pipe 10a. In this case, it is more effective to prevent a gap between the outer flange and the outer peripheral surface of the inner surface resin-coated steel pipe.

  The present invention is not limited to the above, and various modifications are possible. For example, a joint other than a coupling-type joint may be used, and any pipe joint that requires a pipe end anticorrosion treatment in applications such as water supply, hot water supply, and drainage. The piping structure of the present invention can be performed. Moreover, this pipe end anticorrosion member can also be used for inner surface resin-coated steel pipes other than SGP-VA pipes and SGP-PA pipes.

It is a half sectional view of an example of a piping structure provided with a pipe end anticorrosion member concerning an embodiment of the invention. It is the arrow line view which looked at FIG. 1 from A direction. It is the arrow view which looked at FIG. 2 from the B direction. It is sectional drawing which expands and shows the C section of FIG. It is a perspective view of the main body which comprises a pipe end anti-corrosion member. It is sectional drawing which shows an example of a pipe end anti-corrosion member. It is sectional drawing which shows the other example of a pipe end anti-corrosion member.

Explanation of symbols

1: Coupling type joint,
2: housing, 21a, 21b: folded portion,
3: Fastening member, 31: Bar washer, 32: Bar nut, 33a, 33b: Bolt, 34a, 34b: Spacer,
4: packing, 41: cylinder part, 42a, 42b: lip part 5a, 5b: holding member, 51a, 51b: stop ring, 52a, 52b: grip ring, 521a, 521b: locking claw, 53a, 53b: wire ring 6a, 6b: pipe end anticorrosion member, 7: case, 71: bottom plate part, 72: outer flange part, 73: inner flange part, 8: adhesive member 10a, 10b: inner surface resin-coated steel pipe, 11a, 11b: original pipe, 12a, 12b: lining layer

Claims (3)

In a pipe end anticorrosion member comprising a double ring-shaped main body made of a thermoplastic resin and an annular adhesive member in close contact with the end face of the inner surface resin-coated steel pipe, the double ring-shaped main body is formed of the inner surface resin-coated steel pipe. The outer flange portion that engages with the outer peripheral surface, the inner flange portion that engages with the inner peripheral surface of the inner surface resin-coated steel pipe, and the bottom plate portion that integrally connects the outer flange portion and the inner flange portion. With
The length (L1) of the outer flange portion and the length (L2) of the inner flange portion are the ratio of the length (L2) of the inner flange portion and the outer diameter (D) of the inner surface resin-coated steel pipe (L2). / D)
(A) When L2 / D is 0.1 or more and less than 0.3, L2> L1,
(B) When L2 / D is 0.02 or more and less than 0.1, L1> L2
Is set to have a dimensional relationship of
Furthermore, there is no gap between the outer peripheral surface of the inner surface resin-coated steel pipe and the outer flange portion, and the engagement between the inner peripheral surface of the inner surface resin-coated steel pipe and the inner flange portion has a gap. A pipe end anticorrosion member characterized by the above. 2. The pipe end anticorrosion member according to claim 1, wherein the inner surface resin-coated steel pipe is an SGP-PA pipe or an SGP-VA pipe. Comprising an inner surface resin-coated steel pipe according to claim 2, and pipe fittings that require tube end anticorrosion treatment of the inner surface resin-coated steel pipe to be connected, and a tube end anticorrosive member according to claim 1 or claim 2 A piping structure characterized by that.

Images